Prestressed anchorage for tainter gate trunnions and method for doing same



- Feb. 3,1959 DOBE 2,871,664 l PRESTRESSED ANCHORAGE TAI R GATE A'IRUNNIONS AND METHOD FOR DO SAME 2 Sheets-Sheet l Filed Feb. 24. 1955 1N VENTOR M MAMS Feb. 3, 1959 c. DOBELL 2,871,664

PREs'rREssED ANCHORAGE FOR TAINTER GATE TRUNNIONS AND METHOD FOR DOING SAME Filed Feb. 24, 1953 2 SheebS-SheellI 2 *A fao K INVENTOR www M ATTORNEYS PRESTRESSED ANCHORAGE FOR TAINTER GATE TRUNNIONS AND METHOD FOR DOING SAME Curzon Dobell, Bronxvlle, N. Y., assgnor toThe Preload Company, Inc., New York, N. Y., a corporation of Delaware Application February 24, 1953, Serial No. 338,402

13 Claims. (Cl. 61-25) This invention relates to a prestressed anchorage for 'Tainter gate trunnions and to a method for prestressing Tainter gate trunnion anchorages.

In the construction of dams it has been found highly desirable to include spillways or sluiceways. Ordinary practice has led to the use of these spillways, and in conjunction therewith, to the use of gate structures associated with the spillways in order to control the overflow of the Idam. In normal practice these gate structures, co-mmonly referred to as Tainter gates, are pivotally mounted in piers on'either side of the spillway by means of trunnions anchored in the piers. xed bearing blocks are located on the downstream side of the trunnion axis. The'Tainter gate normally consists of a curved skin plate with a set of struts projecting from each end of the plate. Each set of struts terminates in a bearing arm which is mounted for rotation on the trunnion. It is readily apparent that the trunnion is sub jected tohorizontal loading forces whenever the gate closes the spillway or opens the spillway. It has been found in actual experience that these horizontal loading forces will result in movement of the trunnion axis in the pier if the trunnion anchorage is not properly designed. It will be realized that movement of the trunnion axis can weaken the trunnion anchorage and can change the position of the gate relative to the spillway. Thus movement of the trunnion axis shouldbe eliminated or at least minimized as much as possible.

It is, accordingly, an object of the present invention to provide an anchorage for Tainter gate trunnions which will materially reduce the tendency of the trunnions to move due to the application or removal of a horizontal load resulting from Water pressure on the Tainter gate.

It is a further object of the present invention to provide a method for constructing Tainter gate trunnion anchorages that. will have the advantage of stabilizing the axes of the trunnions under loading conditions.

It is a still further object of the present invention to provide an improved trunnion anchorage wherein the reinforcing requirements for the concrete pier in which the trunnions are located will be materially reduced on a weight basis.

It is a still further object of this invention to provide an improved'trunnion anchorage for a Tainter gate and method for producing same which will operate more efficiently and economically than any trunnion anchorage heretofore advanced.

Other and further objects of the present invention will become readily apparent from the details of the following specification, when taken in conjunction with the appended drawings in which:

Figure 1 is a viewin elevation showing the trunnion anchorage of the present invention;

Figure 2 is a view in horizontal section of Figure 1l taken along line 2 2:

Figure 3 is a view in vertical section of Figure 2 taken along line 3 3;

Figure 4 is a view in vertical section along the long To aid in holding the trunnions` ice axis of the pier as shown in Figure 2 .taken along line 4 4; Figure 5 is a view in side elevation showing a modified trunnion anchorage;

Figure 6 is a view in horizontal section of Figure 5 taken along line 6 6;

Figure 7 is a view in verticalisection through the pier shown in Figure 6 taken along the line 7 7; and

Figure 8 is a view in elevation showing one of the rod structures employed in the trunnion anchorage shown in Figure 5.

The present vinvention contemplates prestressing the concrete pier in which the trunnion is located to place the concrete pier under compression. The arrangement is such that loading of the trunnion axis as a result oi the water pressure on'the Tainter gate will cause the concrete pier to become unloaded with respect to compression. The ideal condition will be that the maximum horizontallload resulting from the water pressure on the Tainter gate will exactly counter-balance the compressive load that has been originally placed on the concrete pier. ln carrying out this idea, the concrete bearing block on the downstream side of the trunnion axis is prestressed with high tensile steel wire to another concrete block placed in the interior of lthe pier at a distance upstream of the trunnion axis, as for example 20 feet or more upstream ofthe trunnion axis. If the size of the prestressing force hasv been correctly chosen, then loading of the trunnion axis as a result of Water pressure on the Tainter gate will have the effect of relieving the compression in the co-ncrete without subjecting it to any tensile stress. It is tovbe fully understood, however, that this action will be accompanied byva slight increase in the tension of the --prestressed wires. Thus, it is immediately apparent that there will be a substantial reduction,-if not a complete" reduction, in the movement of the trunnion axis over what was formerly the case with past trunnion anchorages. This reduction in movement is due to the fact that the operation of the anchorage of the present invention `is characterized by small variations of stress in the'concrete. With previously known standard anchorages, the movement of the trunnion axis has been dependent upon large variations of stress in a material such as steel. i

Referring nowto the drawings and, more particularly, to Figures l to 4, inclusive, there is shown the anchorage of the present invention. When the construction of the dam D has been completed to a point where spillway S has been formed and the pier P has been completed up to level L, the concrete bearing block 10 is positioned on the pierP by being concreted overl dowel bars 11 projecting from the concrete below. A movable block 12 is concreted on a paper or bituminous covered smooth surface 19y approximately 2O feet or more upstream of the block 10. Both blocks 10 and 12 are semi-cylindrical and heavily reinforced. l l

The trunnion 5 to be anchored in pier P is positioned betweenbearing block 10 and the pier P. The Tainter.

gate T consists of a skin plate 6 having a set of struts 7 attached adjacent each end of plate 6 with each set of struts 7 terminating in a bearing larm 8. The gate T is supported on each side by a trunnion 5 anchored in a pier P located along the sides of spillway S by means of bearing arm 8 being pivotally housed about trunnion` 5. In Figure 2 there is shown two spillways S with a pier P in between. In this instance a single trunnion 5 serves to support one end of each of two gates T.

Thereafter, form work is erected around block 1i?.y

to creat'e a space for its movement during the stressing oper-ation. The space created by the form work is indicated in Figure 1 by the numeral 13. Concreting of `the pierV is .then continued up to the level of the top of the blocks l() and 12 or even slightly above. HOW- ever, during this concreting step, grooves 14, indicated in Figure 3, approximately one inch deep, are formed in the pier sides between the block s l@ and @12.V Bre,- stressing wires i are then placed in these grooves .1d and wound about blocks lt) and 12. -Therernainder of the pier P can then be completedat ,this time. After the pier concrete has set and hardened,f the prestressing operation can be carried out. iaclis 16 areinserted-in space 13 between the block l2 and the pier. Thereafter, the jacks 16, which can be of the inflatable type, are inated or otherwise operated to cause movement ot block 12 in the upstream direction. When the calculated extension of the prestressing wires 15 vhasbeen accomplished, the space 122 around the jacks 16 can be concreted to hold block l2 inits proper position. Thereafter, the jacks 16 can be removedand the yspaces they occupied can be filled with concrete or, alternatively, the jacks can be left in the pier and iilled in with grout. Finally, the grooves 14 in which the prestressing wires l5 lie can be gunited as indicated at 17' in Figure?, and the open space remaining around the block 12 can also be lled with concrete. The dash line in Figure l identied by the numeral 18 illustrates the probable alteration in the proiile of pier P that will be necessary to accommodate bearing block 1t). This alteration in prole will take place after the trunnion anchorage has been completed.

Utilizing the prestressing method above described to form the prestressed structure above described, it has been found that the resulting structure can be made with approximately one-fth of the steel requirements oi previousfstandard trunnion anchorages. Additionally, it has also beenyfound that the movement of the trunnions is an anchorage as abovedescribed on application of load is about one-twenty-fourth of the movement of a trunnion in a known standard anchorage. It is thus readily apparent that a larger saving in cost and greater eilciency is Vto begained with lthe use of the method and `structure of the present invention over the use of prior known anchorages.

Referring to Figures 5 to 8, Vthere is disclosed av modification of the present invention which utilizes in place of wires or cables and jacks as shown in Figure 1, large diameter steel bars of approximately one-half inch to one andone-eighth inches in diameter. In utilizing bars, the pier P is concreted up to the level L and thereafter bars 20 are horizontally positioned in pier P over the level L by means of suitable form work. The pier P is then concreted above the level L to completion. During finishing of the pier P theA ends 21 ofthe rods 2l) are anchored in the concrete by means of end anchorages which become bonded to the concrete while the remaining portion of each rod 20 is kept from bonding with theconcrete of the pier by suitable means, as for example the bars can be coated with a mastic 22 as shown in Figure 8 which will prevent the rod from bonding with the concrete.

Thereafter, a block 2d is mounted on the pier P at the level L at the ends of the rods 20. This block 2i. includes a box girder 26 having at each end a pair of spaced bearing plates Z7. The trunnion 23 is held in these spaced bearing plates 27 of the box girder 26;. The gate T is supported on trunnion 23 by having the trunnion 23 housed in bearing larm 8. Bearing plates 28 are located on the downstream side of the box girder 26. After the block 24 is in position the rods 20 are prestressed by suitable means, as vfor example, hydraulic jacks or the like. The hydraulic jack is connected to the ends 25 of the rods 2@ and the rods are tensioned and anchored at the ends 2S while in the tension condition. This tensioning oi rods 2t) compressesnthe concrete in the pier P between the ends 21 and 25 -of the rods Ztl. This results in a slight deformation of ythe box girder 26 from a configuration of Vsquare or rectangular in cross-section to slightly trapezoidal Yin crosssection. The trunnion axis of the trunnion 23 will not be subjected to movement until the horizontal load on the Tainter gate T resulting from water pressure on the face of the gate overcomes the prestressing of the rods 21B. The ideal design ycondition would be that the rods Ztl are prestressed an amount equal to the maximum horizontal load condition that can result on the Tainter gate T.

The dash line in Figure 5 identied by `the numeral 3u illustrates the Jprobable alteration in the profile of pier l? that will be necessary to accommodate block 4. This alteration in prole will take place after the trunnion anchorage'has been completed.

While this invention has been described in conjunction with specific embodiments, nevertheless various changes and modications known to one skilled in the art arev within the spirit, scope and contemplation ofthe present invention.

What is claimed is: f

l. in a dam construction including a spillway, a concrete ypier located` on each side of said spillway, a trunnion imbedded in the concrete of said Vpier with one end of said trunnion projecting outwardly from said pier, the imbedded portion of said trunnion being surrounded by concrete in the upstream and downstream directions, and a spillway gate for closing said spillway pivotally supported by said trunnions the improvement that comprises means compressingthe concrete in each pier between a point on the downstream side ofvsaid trunnion and a point on the upstream side of said trunnion when said spillway gate is free from a waterpressure load.

2. ln a darn construction including a spillway, a concrete pier located on each Aside of said spillway; a trunnion imbedded in the concrete of said pier, said trunnion having a horizontally projecting portion `extending outwardly from Vsaid pier, the imbedded portion of said trunnion being surrounded by concrete in the downstream and upstream directions, and a spillway gate ,for closing said spillway pivotally supported by said trunnions the improvement 4that comprises a concrete block supported by each pier and located on the downstream side of each trunnion, and means compressing the conrete in each pier and the concrete in said block between a point on the upstream side of said trunnion and a point on the downstream end of said block when said spillway gate is free from a water pressure load.

3. In a dam construction including a spillway, a con- A crete pier located on each side of said spillway, a trunnion located within each pier, each trunnion being surrounded by concrete in both the downstream and upstream directions relative to said spillway, and aspillway gate for closing said spillway pivotally supported by said trunnions the improvement that comprises a concrete block supported by each pier and located on the downstream side of each ytrunnion a tensioned element extending through each said block andrinto said pier to a point upstream of said trunnion, and means to anchor said tensioned element at the downstream end of said block and at said upstream point.

4. In a dam construction including a spillway, a concrete pier located on each side lof said `spillway', a trunnion located within each pier, and a spillway gate for closing said spillway pivotally supported by said trunnions the improvement that comprises a concrete con crete block supported by each pier and located on` the downstream side of each trunnion, a second concrete block located in each pier at a point upstream of said trunnion, each trunnion being located within the horizontal plane of said blocks with a portion of the concrete of said pier the lfurther improvement of grooves in the sides of each of said piers to receive said tensioned wire.

6. In a dam construction including a spillway, a concrete pier located on each side of said spillway, a trunnion located within each pier, and a spillway gate for closing said spillway pivotally supported by said trunnions the improvement that comprises a concrete block supported by each pier and located on the downstream side of each trunnion, a tensioned rod extending through said block and into said pier to a point upstream of said trunnion, and means anchoring said tensioned rod at the downstream end of said block and at said upstream point,

a portion of said pier extending from said block upstream thereof and surrounding said rod.

7. `In a dam construction including a spilway, a concrete pier located on each side of said 'spillway, a trunnion located within each-pier, said trunnion -being surrounded by concrete in both the upstream and downstream directions, and a spillway gate for closing said spillway pivotally supported by said tmnnions the irnprovement that comprises a concrete block supported by each pier and located on the downstream side of each trunnion, a box girder located in said concrete block, a pair of bearing plates projecting from said box girder for receiving said trunnion, and -means compressing the concrete in said blocks and the concrete in said pier between the downstream end of said block and a point upstream of said trunnion when said spillway gate is free from a water pressure load.

8. In a darn construction including a spillway, a concrete pier located on each side of said spillway, a trunnion located with each pier, and a spillway gate for closing said spillway pivotally supported by said trunnions the improvement that comprises a concrete block supported by each pier and located on the downstream side of each trunnio-n, a box girder located in said concrete block, a pair yof bearing plates projecting from said box girder for receiving said trunnion, a tensioned rod extending through said block and into said pier to a point upstream of said trunnion, and means anchoring said tensioned rod at the downstream end of said block and at said upstream point.

9. In a dam construction as defined in claim S the further improvement of bearing plates on the downstream side of said box girder.

10. A method for anchoring a trunnion for a spillway gate in a concrete pier that comprises locating a trunnion in a concrete pier, surrounding said trunnion with concrete in both the upstream and downstream directions, and compressing the concrete of said pier between a point on the downstream side of said trunnion and a point on the upstream side of said trunnion when said spillway gate is free from a water pressure load.

11. A method for anchoring a trunnion for a spillway gate in a concrete pier that comprises locating a trunnion in a concrete pier, placing a xed concrete block on said pier on the downstream side of said trunnion, surrounding said trunnion with concretev in a horizontal direction from said concrete block to a point upstream thereof, and compressing the concrete of said pier and said block between a point upstream of said trunnion and the downstream end of said block.

l2. A method for anchoring a trunnion for a spillway gate in a concrete pier that comprises locating a trunnion in a concrete pier, placing a fixed block on said pier on the downstream side of said trunnion, placing a movable block in said pier at a point upstream of said trunnion, forming a concrete portion of said pier extending horizontally between said blocks, winding wire around said blocks, moving said movable block in the upstream direction to stress said wire and to compress the concrete portion of said pier between said blocks, and anchoring said movable block.

13. A method for anchoring a trunnion for a spillway gate in a concrete pier that comprises locating a trunnion in a concrete pier, placing a xed concrete block 0n said pier on the downstream side of said trunnion, positioning a rod between the downstream end of said block and a point in said pier upstream of -said trunnion, anchoring said rod at its upstream end by surrounding said rod with a concrete portion of said pier extending from said block to a point upstream thereof, tensioning said rod, and anchoring said rod at the downstream end of said block.

References Cited in the le of this patent UNITED STATES PATENTS 2,617,263 Hill Nov. 11, 1952 FOREIGN PATENTS 236,550 Switzerland of 1945 628,773 Great Britain of 1949 451,798 Italy of 1951 

